[meteorite-list] Images of the Orion Nebula Gives Clues About the Origin of Life on Earth

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Sun, 1 Aug 2010 15:00:58 -0700 (PDT)
Message-ID: <201008012200.o71M0w63019804_at_zagami.jpl.nasa.gov>

30 July 2010

PIO Contact:
Suzanne Frayser
Press Officer, Subaru Telescope, Hilo, HI
+1 808-934-5022
frayser at naoj.org

Science Contact
Tsubasa Fukue
NAOJ, Mitaka, Japan
+81 422-34-3534
tsubasa.fukue at nao.ac.jp

IMAGES OF THE ORION NEBULA GIVE CLUES
ABOUT THE ORIGIN OF LIFE ON EARTH

How did life on Earth begin? One hypothesis is that terrestrial life
began when organics were delivered from outer space during the early,
heavy bombardment phase of Earth's development. We know that several
meteorites (e.g., Murchison) have amino acids with properties similar
to those seen in biological amino acids, the building blocks of life.

An international team of astronomers [1] led by Fukue and Tamura of
the National Astronomical Observatory of Japan conducted research on
the properties of light in a massive star-forming region (BN/KL
nebula) of the Orion Nebula and have investigated a process that may
have played a role in the development of life on Earth.

The origin of what is technically called "biomolecular homochirality"
is a longstanding mystery and an important one to solve, since it
characterizes most life forms on Earth. Chirality refers to the
handedness of an image or phenomenon, which is not identical to the
mirror image of its counterpart, much as the right and left hands are
similar in structure but are opposites and thus not the same.

Homochirality means that a group of molecules exhibit the same
handedness. Therefore, biomolecular homochirality indicates an organic
group of molecules that are characterized by the same handedness.
Terrestrial living material displays homochirality and consists almost
exclusively of one enantiomer, L-amino acid, one of a pair of amino
acids (Fig. 1). Wh
meteorites show enantiomeric excesses of the same handedness as that
seen in biological amino acids. Therefore, the process that produced
the handedness of amino acids in the meteorites may provide clues to
how homochirality developed in life forms on Earth. The larger
question becomes how enantiomeric excesses can be produced and under
what conditions.

Addressing this question became the context within which the research
team worked as they made observations of the Orion Nebula, one of the
brightest and closest regions of high and low mass star formation near
Earth. Since enantiomeric excesses can be produced by circularly
polarized light, the research team focused on observing the degree of
circular polarization in the star-forming region of the Orion Nebula.
They developed the circular polarimeter for SIRPOL on SIRIUS, which is
a wide-field near-infrared camera that works at three near-infrared
bands (J-, H-, Ks-bands) simultaneously
(http://seeds.mtk.nao.ac.jp/~kandori/SIRPOL-e.html). They used SIRPOL
to measure the polarity with SIRIUS on the IRSF (Infrared Survey
Facility) 1.4 m telescope in South Africa.

Their results include the presentation of a wide-field and deep
near-infrared (Ks band: 2.14 micron) circular polarization image of
the Orion Nebula (Fig. 2), where massive stars and many low-mass stars
are forming. This image reveals a circularly polarized region that is
spatially extended around the BN/KL nebula, a massive star-forming
region. The circular polarization here is high and significant,
extending over a region about 400 times the size of the Solar System,
an area observed that is much larger than that of previous studies.

Other regions contrast with this one and show no significant circular
polarization. Unlike the BN/KL nebula, most of the low-mass young
stars do not demonstrate a detectable extended structure in either
linear or circular polarization. The researchers infer that their
results indicate a process that could have played a role in the
develo
if our Solar System formed in a massive star-forming region like
Orion's, then circularly polarized radiation could have induced
enantiomeric excesses in the parent bodies of meteorites and
subsequently delivered to Earth.

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This research was published in 2010 in Origins of Life and Evolution
of Biospheres (40, 335, DOI:10.10007/s11084-010-9206-1). [2]

Figures can be accessed by visiting the Subaru Telescope website at
www.SubaruTelescope.org <http://www.SubaruTelescope.org> and then
referring to the full article in
"Topics".

Figure 1: This shows images of the structures of the two enantiomers,
L-alanine and D-alanine, which are mirror images of the other. Black
bars express atomic bonds. Red, orange, blue, green spheres express
atoms of hydrogen, carbon, nitrogen, and oxygen, respectively. (This
image was provided by NAOJ, the National Astronomical Observatory of
Japan)

Figure 2: This image was captured using SIRPOL, the SIRIUS camera's
mode of measuring circular polarity. It shows the degree of circular
polarization of the Orion star-forming region. Yellow color expresses
left-handed circular polarization, where the electric vector of light
is rotated anticlockwise. Red color expresses right-handed circular
polarization. The black bar denoted by (A) expresses about 400 times
the size of the Solar System, and the bar by (B) shows about 100 times
the size of the Solar System. (Image provided by NAOJ, the National
Astronomical Observatory of Japan.)

Notes:

[1] Research group: Tsubasa Fukue (NAOJ), Motohide Tamura (NAOJ /
Graduate University of Advanced Science), Ryo Kandori (NAOJ), Nobuhiko
Kusakabe (NAOJ), James H. Hough (Centre for Astrophysics Research,
Science and Technology Research Institute, University of
Hertfordshire), Jeremy Bailey (School of Physics, University of New
South Wales), Douglas C. B. Whittet (New York Center for Astrobiology
and Department of Physics and Astronomy, Rensselaer Polytechnic
Institute), Philip W. Luc
and Technology Research Institute, University of Hertfordshire),
Yasushi Nakajima (Department of Astrophysics, Nagoya University /
NAOJ), Jun Hashimoto (Graduate University of Advanced Science)

[2] The published paper is entitled "Extended High Circular
Polarization in the Orion Massive Star-Forming Region: Implications
for the Origin of Homochirality in the Solar System". The article can
also be obtained in Springer's open access:
http://www.springerlink.com/content/q0k1k74u76451557/
Received on Sun 01 Aug 2010 06:00:58 PM PDT